We investigated whether 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced ear inflammation is exacerbated in type 2 diabetic db/db mice, and if it is prevented by the control of blood glucose levels. Ear inflammation was assessed by ear thickness and the mRNA expression of the pro-inflammatory cytokines IL-1beta, IL-6, and TNF-alpha. Six-week-old db/db mice received an insulin treatment combined with exercise training daily for three weeks to lower blood glucose to normal levels. The other db/db group and their control (db/m) mice received saline without exercise training. TPA-induced ear swelling peaked after 8 h in db/m mice and after 32 h in db/db mice. The gene expression levels of cytokines 24 and 32 h after the TPA treatment were higher in db/db mice than in db/m mice. The insulin treatment combined with exercise training significantly suppressed blood glucose and HbA1c levels in 9-week-old db/db mice, but did not prevent the TPA-induced inflammatory response. These results revealed that TPA-induced ear inflammation was exacerbated in db/db mice and was not prevented by the insulin treatment combined with exercise training.